商陆钾离子吸收特性研究

采用K+浓度分别为50、200和800 μmol/L的Hoagland营养液培养商陆和水稻,观测商陆的形态和生理指标,比较商陆和水稻的K+吸收动力学参数米氏常数(Km)、最大吸收速率(Imax)和钾离子吸收最低临界浓度值(Cmin).结果表明,各处理的商陆能正常生长,光合速率、蒸腾速率、株高和根冠比等的差异不显著;在低...     

Binding Sites for Ca2+-Channel Effectors and Ryanodine in Periplaneta americana—Possible Targets for New Insecticides

The calcium channel and the ‘calcium release channel’ of muscle membrane of the cockroach Periplaneta americana have been characterized. Biological assays with calcium channel blockers and ryanodine on different insects and acari revealed pronounced insecticidal effects with ryanodine, but not with calcium channel blockers, at concentrations between 0·1 and 300 μg ml⁻¹. Skeletal muscle membranes derived either from the tubular network or from the sarcoplasmatic reticulum of P. americana were characterized with respect to the binding of the dihydropyridine (DHP) [³H]isradipine (PN 200-110), the phenyl-alkylamine [³H]verapamil and the alkaloid [³H]ryanodine. Preliminary binding studies with the benzothiazepine [³H]diltiazem suggest a low-affinity binding site with a IC₅₀ value of 3·3 μM . All binding sites tested were sensitive to treatment with proteinase K. Optimal conditions for binding of the radioligand ryanodine revealed the highest specific binding at pH 8 and at calcium chloride concentrations between 100 and 500 μM . EGTA at 10 μM abolished 95% of the ryanodine binding. Binding studies with calcium channel binding sites revealed a pronounced effect of low Ca²⁺ concentrations on specific isradipine binding, whereas verapamil and diltiazem binding were only reduced by the presence of 200 μM EGTA. With respect to high Ca²⁺ concentrations, specific binding of diltiazem, isradipine and verapamil was reduced by 73, 40 and 20%, respectively, at 5 mM Ca²⁺. Radioligand binding experiments showed high-affinity binding sites for ryanodine and isradipine. K_D values of 0·95 nM (B_max=550 fmol mg⁻¹ protein) and 0·75 nM (B_max=213 fmol mg⁻¹ protein) were determined respectively. A lower-affinity binding site was identified in binding studies with verapamil (K_D=7·4 nM and B_max=27 fmol mg⁻¹ protein). [³H]isradipine displacement studies with several dihydropyridines revealed the following ranking of affinity: nitrendipine>isradipine>Bay K8664≪nicardipine. Displacement of [³H]verapamil binding by effectors of the phenylalkylamine binding site showed that bepridil and S(-)verapamil had the highest affinities of the compounds tested followed by (±)verapamil, nor-methylverapamil and R(+)verapamil.     

基于转录组测序的油梨 EST-SSR 引物开发

利用转录测序技术,开发油梨表达序列标签-简单重复序列（EST-SSRs）,为 SSR 标记在油梨种质资源鉴定、品种选育及遗传连锁图谱构建奠定基础。采用 Illumina 二代测序的技术,共获得 37 639 条无冗余的序列,对其进行 SSR搜索,共获得 6 419 条简单序列重复（SSR）。利用 Primer 3.0 软件设计 SSR 引物,并以 11 份油梨种质筛选多态性引物。基于转录组序列开发出的 EST-SSR 的分布频率为 17.05%。在油梨 EST-SSR 中,单核苷、二核苷和三核苷的重复占主导,占总数的 99.07%。单、二、三核苷酸重复单元分别占总 SSR 的 37.47%、31.80%和 29.80%;出现频率最高的二核苷酸重复基元是 AG/CT,占总数的 29.15%,出现最高的三核苷酸重复基元为 AAG/CTT,占 12.01%。随机选择 315 个SSR 位点合成引物,经 11 份油梨种质筛选鉴定,227 对引物可扩增获得产物,有效扩增率为 72.06%;其中 34 对引物表现出良好多态性,占有效引物的 12.78%,占总引物的 10.79%。在 34 对多态性引物中,每对引物扩增等位基因数 2~12个。利用高通量测序开发 SSR 引物有较好的实性,开发获得的 34 个具有多态性的油梨 SSR 标记可用于研究油梨及其相关近缘物种的遗传变异。     

基于转录组测序的油梨 EST-SSR 引物开发

利用转录测序技术,开发油梨表达序列标签-简单重复序列（EST-SSRs）,为 SSR 标记在油梨种质资源鉴定、 品种选育及遗传连锁图谱构建奠定基础。采用 Illumina 二代测序的技术,共获得 37 639 条无冗余的序列,对其进行 SSR 搜索,共获得 6 419 条简单序列重复（SSR）。利用 Primer 3.0 软件设计 SSR 引物,并以 11 份油梨种质筛选多态性引物。 基于转录组序列开发出的 EST-SSR 的分布频率为 17.05%。在油梨 EST-SSR 中,单核苷、二核苷和三核苷的重复占主 导,占总数的 99.07%。单、二、三核苷酸重复单元分别占总 SSR 的 37.47%、31.80%和 29.80%;出现频率最高的二核 苷酸重复基元是 AG/CT,占总数的 29.15%,出现最高的三核苷酸重复基元为 AAG/CTT,占 12.01%。随机选择 315 个 SSR 位点合成引物,经 11 份油梨种质筛选鉴定,227 对引物可扩增获得产物,有效扩增率为 72.06%;其中 34 对引物 表现出良好多态性,占有效引物的 12.78%,占总引物的 10.79%。在 34 对多态性引物中,每对引物扩增等位基因数 2~12 个。利用高通量测序开发 SSR 引物有较好的实用性,开发获得的 34 个具有多态性的油梨 SSR 标记可用于研究油梨及 其相关近缘物种的遗传变异。     

刈割和施肥对热研4 号王草生物量影响初报

采用随机区组设计研究刈割时间、刈割次数和施肥量对热研4号王草生物量的影响,结果表明,热研4号王草在海南夏季6～8月份60 d的生长期内,刈割时间间隔20 d、刈割3次的处理,第2次刈割的鲜草生物量最大,且不受施肥量的影响。但当施肥量为1 563 kg/hm~2时的牧草生物量最大,为41 340.10 kg/hm~2;刈割时间间隔30 d、刈割2次的处理,除施肥量为3 127 kg/hm~2的处理外,第1次刈割均比第2次刈割产量高,且差异显著。在相同施肥量下,就单次刈割生物量和总生物量而言,刈割时间间隔越长、刈割次数越低,鲜草生物量就越大,刈割时间为50 d和60 d之间鲜草生物量差异不显著,而与其他处理差异显著,不同的施肥条件下,在刈割时间间隔40 d时,施肥量为4 690 kg/hm~2比施肥量为1 563 kg/hm~2的产量显著增加。在刈割时间间隔50 d和60 d时,随着施肥量的增加,产量并无差异。     

鳄梨导管分子及穿孔板观察研究

运用细胞图像分析系统及显微照相的方法,观察研究鳄梨次生木质部导管分子。结果发现,鳄梨次生木质部导管分子中存在着许多不同的样式,并且导管分子穿孔板存在着6种类型:①两端均为一个单穿孔板;②一端为一个单穿孔板,另一端为梯状穿孔板;③两端均为梯状穿孔板;④一端为梯状穿孔板,另一端为奇特样式穿孔板;⑤两梯状穿孔板分别位于同一导管分子相对的侧壁互相对应;⑥一单穿孔板和一梯状穿孔板分别位于同一导管分子相对的侧壁互相对应;还存在一些过渡类型。管间纹孔式为互列纹孔式,导管射线间纹孔式为横列、纵列刻痕状纹孔式。部分导管分子侧壁具有纹饰。分别对其进行了描述,并从导管分子个体发育与系统发育的角度进行了讨论。     

盐胁迫对美国白蜡和滨梅根系超微结构的影响

应用透射电子显微镜观察0（对照）,3,9g／L盐胁迫4个月下美国白蜡和滨梅根系细胞超微结构的变化。结果表明：低盐（3g／L）胁迫下,美国白蜡根系细胞质凝聚,质壁分离明显,细胞器降解严重,细胞核核膜部分解离,细胞壁基本正常;滨梅变化不明显。高盐（9g／L）胁迫下,美国白蜡受到深度伤害,细胞质进一步降解,质壁分离严重;滨梅细胞内降解物质明显增多,细胞器降解,细胞核染色质浓度降低,核膜模糊,细胞质膜局部发生内陷,没有发生明显的质壁分离。比较而言,美国白蜡根系细胞受损较为严重,滨梅表现出较强的抗盐性。     

Soil Fertility Improvement by Litter Decomposition and Inoculation with the Fungus Mortierella sp. in Avocado Plantations of Colombia

Litter decomposition is a major process in nutrient recycling, despite that few studies have considered this in soil fertility management. The aim of this study was to evaluate the effect of litter decomposition and its inoculation with the fungus Mortierella sp. on soil fertility parameters in Andisols cultivated with avocado cv. Hass. Litterbags containing avocado leaves either uninoculated or inoculated were distributed around the trees. As control litter was not allowed to accumulate on the soil surface. Eighteen months later soil samples were collected just below uninoculated and inoculated litterbags and control sites. Soil pH, potassium, calcium, phosphorus, magnesium, and boron significantly increased with litter and in some sites the increase was higher with inoculation. By contrast, soil aluminum, iron, and manganese were significantly lower in the presence of litter (uninoculated and inoculated), whereas zinc was significantly higher when litter was present.     

油梨和羊奶果果肉粗提物对α-葡萄糖苷酶的体外抑制

收集不同油梨和羊奶果资源,对油梨和羊奶果果肉粗提物进行α-葡萄糖苷酶的体外抑制活性实验。结果表明:16份油梨果肉对α-葡萄糖苷酶抑制活性较弱,而9份羊奶果果肉对α-葡萄糖苷酶抑制活性较强,其中羊奶果6号对α-葡萄糖苷酶抑制活性最强,达到99.84%,仅次于阿卡波糖。     

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling‐safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.